Increased levels of insurgent warfare have led to the need to protect vehicles, structures and/or personnel from munitions typically used in this type of warfare, such as small arms fire and improvised explosive devices (IEDs). While a variety of means are available to minimize casualties from these threats, the use of suitable armour remains an important last line of defence. As a result of the need to protect a large number of potential targets while not hindering their mobility, it is also important to be able to provide armour that is lightweight and relatively inexpensive.
Armour has, of course, traditionally relied on thick layers of steel or other metals. Steel is however very heavy and inflexible, it is difficult to shape and use in all but simple configurations. Heavily armoured vehicles are therefore slow and tend to have a higher centre of gravity making them vulnerable to roll over when they encounter an angular moment such as that generated by a blast, terrain feature or sharp directional change. Steel is generally unsuitable for use in structures such as temporary buildings or tents erected in theatre.
For temporary structures, the most common method of providing ballistics protection is the use of sandbags. Hescobastions are well known large sandbags which can be used as military fortifications but they require large amounts of sand to be present in an area and possibly also an earth mover to fill them. Stacking hescobastions to provide head high armour protection is extremely difficult without lifting equipment like a fork lift.
The present inventors sought new types of armour which offer alternatives to the likes of hescobastions. In particular, the inventors sought an armour material that can be moulded into shape in the field and which is lightweight. As noted above, armour materials tend to be hard and inflexible. It is difficult to mould armour into curved shapes without the use of moulds and enormous temperatures to melt the armour before use. Moreover, armouring temporary structures erected in the field of battle is very difficult. Whilst sandbags are often used for this purpose, these are heavy and are limited by a ready source of sand. They cannot really be moulded to any fixed shape.
The present inventors offer a solution to this problem. By using a multilayer structure having at least a hydrogel based layer and an armour layer that becomes mouldable when wet but non mouldable when dry, the inventors can offer armours that are mouldable. Thus, armour could be moulded to fit the side of a vehicle or temporary structure by wetting it. Thereafter, the armour dries out naturally in the sun, becomes non mouldable but retains the moulded shape.
No one before has considered the idea of mouldable armour based on hydration and dehydration thereof.